Composite flotation depressor for inhibiting organic matter and silicon in phosphogypsum and application thereof

Abstract

The application discloses a kind of synchronous inhibition phosphogypsum in organic matter and the application of compound flotation depressor of silicon, and compound flotation depressor includes mercapto acid type inhibitor, mercapto ammonium type inhibitor and sodium silicate.The application of compound flotation depressor is as follows: the byproduct phosphogypsum from industrial wet-process phosphoric acid is carried out granularity grading, and-100~+350 mesh fraction enters flotation operation;Actual phosphogypsum of-100~+350 mesh fraction is carried out pulp conditioning, and slurry concentration is adjusted to 15%-30%, adjusting agent is added to adjust pH to 1.8-2.5, and water solution of compound flotation depressor is added, and collector and frother are sequentially added, and flotation is carried out, to obtain concentrate and tailings.The compound flotation depressor provided by the application can simultaneously inhibit silicon dioxide and organic matter in phosphogypsum, realize efficient separation of CaSO4·2H2O and organic matter, silicon dioxide and other impurities in phosphogypsum, and simultaneously greatly improve the whiteness and purity of product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phosphogypsum purification, and particularly relates to a composite flotation inhibitor for simultaneously inhibiting organic matter and silicon in phosphogypsum and application thereof. BACKGROUND

[0002] Phosphogypsum is a by-product of the process of preparing phosphoric acid by the wet method, and usually 4.5-5.5 tons of phosphogypsum are produced per ton of phosphoric acid. According to statistics, about 600 million tons of phosphogypsum have been accumulated in China, and it is estimated that the total amount of phosphogypsum accumulation will increase to about twice the present amount in the next 5-20 years. At present, the comprehensive utilization rate of phosphogypsum in the world is about 40%, and most of the phosphogypsum is treated by open-air stacking, which not only occupies a large amount of land resources and causes geological risks, but also causes large-area soil and water pollution due to the dissolution of a large amount of soluble phosphorus, fluorine, heavy metals and other impurities.

[0003] Phosphogypsum mainly consists of CaSO4·2H2O, and also contains various impurities, mainly including silicon dioxide, organic matter, soluble phosphorus, soluble fluorine, heavy metal ions and the like, which seriously deteriorate the performance of phosphogypsum resource products. At present, phosphogypsum is mainly used in low-value-added fields such as cement, chemical raw materials, soil conditioner and roadbed. The purity and whiteness of CaSO4·2H2O in phosphogypsum are important technical indicators for expanding its application, and the purification and whitening of phosphogypsum can greatly improve its added value. Among them, the main impurities affecting the purity and whiteness of phosphogypsum are silicon dioxide and organic matter. Therefore, efficient removal of silicon dioxide and organic matter impurities in phosphogypsum is the key to realizing its bulk and high-value utilization.

[0004] Phosphogypsum purification and whitening mainly includes acid leaching, gravity separation, water washing, calcination and flotation processes. Patent CN111302377A discloses a method for removing impurities and whitening phosphogypsum, which adopts a combined process of acid leaching, flotation and gravity separation in sequence. The process flow is complex, and the method involves multiple dehydration stages, which is high in cost. Moreover, the use of acid leaching will generate a large amount of wastewater that needs to be treated. Patent CN114605094A discloses a method for improving the whiteness and purity of phosphogypsum by ore dressing and smelting. However, the method needs to add ammonium chloride for grinding and calcination after flotation, which is high in energy consumption and causes great harm to the environment. The flotation method can effectively remove organic matter and silicon dioxide and other impurities in phosphogypsum, greatly improving its purity and whiteness. At present, phosphogypsum purification is mainly achieved by stepwise inhibition of organic matter and silicon dioxide, which is relatively complex in process, high in energy consumption and reagent consumption. It is urgent to develop a low-cost, efficient and green reagent and method for simultaneously inhibiting organic matter and silicon dioxide in phosphogypsum.

[0005] In summary, in view of the problems of the current phosphogypsum purification and whitening technology, such as complex process flow, high cost, serious environmental pollution, poor inhibition effect of conventional flotation depressants, and single capacity, it is of great significance to develop a multifunctional depressant which can simultaneously and efficiently inhibit organic matter and silicon impurities in phosphogypsum and improve the whiteness and yield of phosphogypsum products in the flotation process. SUMMARY

[0006] The present application aims at the above-mentioned deficiencies in the prior art, and provides a non-toxic and environmentally friendly, highly adaptable, efficient and rapid composite flotation depressant for simultaneously inhibiting organic matter and silicon in phosphogypsum in flotation and its application.

[0007] The composite flotation depressant for simultaneously inhibiting organic matter and silicon in phosphogypsum comprises a mercapto acid inhibitor, a mercapto ammonium inhibitor and sodium silicate.

[0008] Further, the flotation depressant comprises the following components in mass fraction: 1-2 parts of mercapto acid inhibitor, 1-2 parts of mercapto ammonium inhibitor, and 1-3 parts of sodium silicate.

[0009] Further, the carbon chain length of the mercapto acid inhibitor is 2-16, and the carbon chain length of the mercapto salt inhibitor is 2-16.

[0010] Further, the salt ions of the mercapto salt inhibitor include but are not limited to NH4 + , Na + , K + , and Fe 2+ .

[0011] Further, the mercapto acid inhibitor comprises one or more of mercapto acetic acid, mercapto propionic acid, mercapto butyric acid, 11-mercapto undecanoic acid, 12-mercapto dodecanoic acid, and 16-mercapto hexadecanoic acid.

[0012] Further, the mercapto salt inhibitor comprises one or more of mercapto acetate, mercapto propionate, mercapto butyrate, 11-mercapto undecanoate, 12-mercapto dodecanoate, and 16-mercapto hexadecanoate.

[0013] The application of the composite flotation depressant as described above classifies the by-product phosphogypsum from industrial wet-process phosphoric acid by particle size, and the -100 to +350 mesh particle size is used in the flotation operation; the actual phosphogypsum in the -100 to +350 mesh particle size is thickened, the pulp concentration is adjusted to 15% to 30%, an adjusting agent is added to adjust the pH value to 1.8 to 2.5, an aqueous solution of the composite flotation depressant is added, a collector and a frother are sequentially added, and flotation is performed to obtain a concentrate and a tailing.

[0014] The preparation method of the aqueous solution of the composite flotation depressant specifically comprises mixing raw materials and water in proportion, and rapidly stirring at low temperature for a certain time to obtain a multifunctional depressant for simultaneously depressing organic matter and silicon dioxide in the phosphogypsum in the flotation.

[0015] Further, the collector is configured by dodecylamine and hydrochloric acid.

[0016] Further, the frother is methyl isobutyl carbinol.

[0017] According to the analysis of the phosphogypsum, the main coloring substance of the phosphogypsum is organic matter, and the main impurities are metal oxides and silicon dioxide (most phosphogypsums mainly contain these two impurities, only the contents are different). Sodium silicate can generate silica gel particles and HSiO3 2- Preferentially adsorbs on the surfaces of quartz and silicate minerals, and depresses the combination of quartz and silicate minerals and the collector; the depression mechanism of the mercaptoammonium-based depressant and the mercapto acid-based depressant is to form stable complexes by combining with metal ions, so that the activity of metal enzymes is inhibited. In this process, the mercapto group (-SH) in the mercaptoammonium-based depressant and the mercapto acid-based depressant plays a key role, and they form complexes with metal ions, so that the metal ions cannot combine with the substrate, thereby inhibiting the catalytic effect of the enzyme. In addition, the mercapto acid-based depressant can also reduce the pH value of the medium by providing hydrogen ions, thereby further enhancing its inhibitory effect. At the same time, as an organic reagent, according to the principle of similar dissolves similar, the mercapto acid-based depressant will adhere to or wrap most of the organic matters, and inhibit the floating thereof. By adjusting the amount of the three depressants, the steric hindrance can be reduced, and a synergistic effect can be achieved to inhibit various impurities and coloring substances, and improve the whiteness of the flotation product.

[0018] Compared with the prior art, the present application has the following remarkable effects:

[0019] (1) The preparation process of the composite flotation depressant provided by the present application is simple, the production cost is low, no special process is needed, and the present application is green and environmentally friendly;

[0020] (2) Compared with the existing sodium silicate, starch and other inhibitors, the composite flotation inhibitor provided by the application can simultaneously inhibit the silicon dioxide and organic matter in the phosphogypsum, realize efficient separation of CaSO4·2H2O and organic matter, silicon dioxide and other impurities in the phosphogypsum, and simultaneously greatly improve the whiteness and purity of the product;

[0021] (3) Compared with the traditional two-step method of removing organic matter and silicon dioxide respectively, the process flow is shorter and the amount of reagent is less when using the composite flotation inhibitor prepared by the application for flotation. DETAILED DESCRIPTION

[0022] The following are specific embodiments of the application, which further describe the technical solutions of the application, but the application is not limited to these embodiments.

[0023] Comparative Example 1:

[0024] After grading the by-product phosphogypsum of wet-process phosphoric acid in Yichang, Hubei, the 100-+350 mesh particle size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, and the air charge was 0.2 m 3 / (m 2 ·min). The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the inhibitor sodium silicate was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the foaming agent MIBC was added after continuing to stir for 1 min, and the air was turned on after waiting for two minutes, and the foam was scraped and separated.

[0025] The specific results are shown in Table 1. When sodium silicate was used as the inhibitor, the concentrate yield obtained in Comparative Example 1 was 75.69%, the concentrate whiteness was 49.50%, and the purity of CaSO4·2H2O in the concentrate was 93.78%.

[0026] Comparative Example 2:

[0027] After grading the by-product phosphogypsum of wet-process phosphoric acid in Yichang, Hubei, the 100-+350 mesh particle size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, and the air charge was 0.2 m 3 / (m 2 ·min). The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the inhibitor starch was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the foaming agent MIBC was added after continuing to stir for 1 min, and the air was turned on after waiting for two minutes, and the foam was scraped and separated.

[0028] The specific results are shown in Table 1, using starch as the depressant, the concentrate yield obtained by Comparative Example 2 is 75.58%, the concentrate whiteness is 49.50%, and the purity of CaSO4·2H2O in the concentrate is 94.14%.

[0029] Comparative Example 3:

[0030] The Hubei Yichang wet-process phosphoric acid by-product phosphogypsum was classified, and the 100-+350 mesh size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, and the air charge was 0.2 m 3 / (m 2 ·min). The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the depressant sodium hexametaphosphate was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the frother MIBC was added after 1 min of continuous stirring, and the air was turned on after waiting for 2 min, and the froth was scraped and separated.

[0031] The specific results are shown in Table 1, using sodium hexametaphosphate as the depressant, the concentrate yield obtained by Comparative Example 3 is 44.40%, the concentrate whiteness is 50.62%, and the purity of CaSO4·2H2O in the concentrate is 94.53%.

[0032] Comparative Example 4:

[0033] The Hubei Yichang wet-process phosphoric acid by-product phosphogypsum was classified, and the 100-+350 mesh size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, and the air charge was 0.2 m 3 / (m 2 ·min). The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the depressant sodium hexametaphosphate was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the frother MIBC was added after 1 min of continuous stirring, and the air was turned on after waiting for 2 min, and the froth was scraped and separated.

[0034] The specific results are shown in Table 1, using sodium hexametaphosphate as the depressant, the concentrate yield obtained by Comparative Example 3 is 44.40%, the concentrate whiteness is 50.62%, and the purity of CaSO4·2H2O in the concentrate is 94.53%.

[0035] Comparative Example 5:

[0036] The Hubei Yichang wet-process phosphoric acid by-product phosphogypsum was classified, and the 100-+350 mesh size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, and the air charge was 0.2 m 3 / (m2 The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the mixed reagent of mercaptoacetic acid and mercaptoacetic acid ammonium was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the frother MIBC was added after 1 min of continuous stirring, and the flotation was started after waiting for 2 min.

[0037] The specific results are shown in Table 1. When the mixed reagent of mercaptoacetic acid and mercaptoacetic acid ammonium was used as the depressant, the concentrate yield obtained in Comparative Example 5 was 81.31%, the concentrate whiteness was 49.35%, and the purity of CaSO4·2H2O in the concentrate was 94.32%.

[0038] Comparative Example 6:

[0039] The Hubei Yichang by-product phosphogypsum of wet-process phosphoric acid was classified, and the 100-+350 mesh size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, the air charge was 0.2 m 3 / (m 2 The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the mixed reagent of mercaptoacetic acid and mercaptoacetic acid ammonium was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the frother MIBC was added after 1 min of continuous stirring, and the flotation was started after waiting for 2 min.

[0040] The specific results are shown in Table 1. When the mixed reagent of mercaptoacetic acid and mercaptoacetic acid ammonium was used as the depressant, the concentrate yield obtained in Comparative Example 5 was 81.31%, the concentrate whiteness was 49.35%, and the purity of CaSO4·2H2O in the concentrate was 94.32%.

[0041] Example 1:

[0042] The Hubei Yichang by-product phosphogypsum of wet-process phosphoric acid was classified, and the 100-+350 mesh size phosphogypsum was used as the flotation feed and was fed into a flotation machine for flotation. The rotation speed of the flotation machine was set to 1650 r / min, the air charge was 0.2 m 3 / (m 2 The pulp concentration was adjusted to 20%, sulfuric acid was added to adjust the pulp pH to 2.0, 400 g / t of the mixed reagent of mercaptoacetic acid and mercaptoacetic acid ammonium was added, 200 g / t of the collector dodecylamine was added after uniform stirring, 300 g / t of the frother MIBC was added after 1 min of continuous stirring, and the flotation was started after waiting for 2 min.

[0043] The composite flotation inhibitor used in this example was a mixed reagent of sodium silicate, mercaptoacetic acid and mercaptoacetic acid ammonium in a mass ratio of 2:1:1.

[0044] The specific results are shown in Table 1, when the composite flotation depressant of Example 1 is used as the depressant, the concentrate yield of Example 1 is 81.88%, the whiteness of the concentrate is 50.21%, and the purity of CaSO4·2H2O in the concentrate is 94.50%.

[0045] Table 1: Analysis of flotation feed and concentrate of each example

[0046]

[0047] From the comparison of the effects of each depressant in Table 1, it can be found that in Example 1, when the composite flotation depressant prepared by the present application is used, the purity of CaSO4·2H2O in the phosphogypsum concentrate product is optimal, and the whiteness is significantly improved. The above results verify the important role of the composite flotation depressant prepared by the present application in the synchronous removal of organic matter and silicon dioxide in phosphogypsum. The composite flotation depressant prepared by the present application provides an important idea for the optimization of the flotation and purification whitening process of phosphogypsum.

[0048] The particle size analysis data of the phosphogypsum obtained by the wet-process phosphoric acid production are shown in Table 2. From Table 2, it can be found that SiO2 is mainly concentrated in the particle size of -500 mesh and +100 mesh, and SO3 and CaO are mainly distributed in the middle particle size of -100+500. It is not difficult to infer that the purity of CaSO4·2H2O in the particle size of -100+500 is higher. The experiment does not use the particle size of -100+500 for flotation but uses the particle size of -100+350 as the flotation feed. This is because in actual industrial production, it is difficult to sieve 500 mesh, and the fine particle size of -350 is easy to be muddy, causing difficulty in flotation of -100+350 particle size and poor control of reagent dosage. The whiteness and purity distribution of each particle size in the raw ore are shown in Table 3.

[0049] Table 2: XRF results of main oxides in each particle size (%)

[0050]

[0051] Table 3: Whiteness and purity distribution of each particle size in the raw ore of phosphogypsum

[0052]

[0053] The above is not involved, apply to the prior art. Although some specific embodiments of the present application have been described in detail by examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present application, those skilled in the art can make various modifications or supplements or adopt similar ways to replace the described specific embodiments, but not deviate from the direction of the present application or beyond the scope defined by the appended claims. Those skilled in the art should understand that any modification, equivalent replacement, improvement, etc. made according to the technical essence of the present application to the above embodiments shall be included in the protection scope of the present application.

Claims

1. The use of a composite flotation depressant for simultaneously depressing organic matter and silica in phosphogypsum, characterized in that: The flotation depressant comprises components in the following mass fractions: 1-2 parts of a mercapto acid type depressant, 1-2 parts of a mercapto salt type depressant, 1-3 parts of sodium silicate; The by-product phosphogypsum from industrial wet-process phosphoric acid is subjected to particle size grading, and the -100+350 mesh fraction is subjected to flotation operation; the actual phosphogypsum in the -100+350 mesh fraction is subjected to pulp conditioning, the pulp concentration is adjusted to 15-30%, an adjusting agent is added to adjust the pH value to 1.8-2.5, an aqueous solution of a composite flotation depressant is added, a collector and a frother are sequentially added, and flotation is performed to obtain a concentrate and a tailing.

2. The use of a composite flotation depressant for the simultaneous depression of organic matter and silica in phosphogypsum according to claim 1, characterized in that: The mercapto acid type depressant has a carbon chain length of 2-16; and the mercapto salt type depressant has a carbon chain length of 2-16.

3. The use of a composite flotation depressant for the simultaneous depression of organic matter and silica in phosphogypsum according to claim 1, characterized in that: The salt ions of the thiol salt inhibitor include NH4 + , Na + , K + , Fe 2+ .

4. The use of a composite flotation depressant for the simultaneous depression of organic matter and silica in phosphogypsum according to claim 1, characterized in that: The mercapto acid type depressant comprises one or more of mercapto acetic acid, mercapto propionic acid, mercapto butyric acid, 11-mercapto undecanoic acid, 12-mercapto dodecanoic acid and 16-mercapto hexadecanoic acid.

5. The use of a combined flotation depressant for the simultaneous depression of organic matter and silica in phosphogypsum according to claim 1, characterized in that: The mercapto salt type depressant comprises one or more of mercapto acetate, mercapto propionate, mercapto butyrate, 11-mercapto undecanoate, 12-mercapto dodecanoate and 16-mercapto hexadecanoate.

6. The use of a composite floatation depressant according to claim 1, characterized in that: The collector is prepared by using dodecylamine and hydrochloric acid.

7. The use of a composite floatation depressant according to claim 1, characterized in that: The frother is methyl isobutyl carbinol.

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